It's
not eternal wrath, that's the whole point! It's being born dead in our sins and the grave, that's the punishment for our sins. We know it's not eternal wrath because there was a limit to Christ's suffering. He suffered what it was like to be dead in sin and cut off from God for three hours and He went down into the grave/Hades and the reason it could not hold Him, was not because He is God, but because He had no sin in His humanity.
It's also how we know Christ died for all because death has to give everyone up and hand them over to Christ, the saved and unsaved alike. Death and Hades are empty when thrown into the lake of fire.
Revelation 20:13
The sea gave up the dead that were in it, and
death and Hades gave up the dead that were in them, and each person was judged according to what they had done.